3.1.1-Atomic structure

Question 1

Definition Atomic number

Answer 1

The number of protons in a atom.

Question 2

Relative charge of:
Proton 
Neutron 
Electron 
Relative mass of:
Proton 
Neutron 
Electron

Answer 2

Proton. +1
Neutron. 0
Electron. -1

Proton. 1
Neutron. 1
Electron. 0

Question 3

Definition of atomic mass

Answer 3

The number of protons and neutrons in an atom

Question 4

Definition of an isotope

Answer 4

When atoms of an element have a different number of neutrons

Question 5

The order of processes in mass spectrometry

Answer 5

1) Electron impact ionisation / electrospray ionisation
2) acceleration
3) ion drift
4) detection

Question 6

Explain Electron impact ionisation

Answer 6

High energy electrons are fired from an electron gun to bombard gaseous atoms and knock of an electron it then forms an ion.

Question 7

Explain electrospray ionisation

Answer 7

Technique for ionising molecules. Dissolved sample passes through a needle attached to a positive voltage supply. Particles gain protons forming ions.

Question 8

What is the best ionisation for inorganic molecules and elements.

Answer 8

Electron impact ionisation

Question 9

What is best ionisation for organic molecules and why?

Answer 9

Electrospray ionisation because it dosent fragment the molecules.

Question 10

Explain acceleration

Answer 10

Positive ions in a mass spectrometer are accelerated by magnetic field to all have same kinetic energy.

Question 11

Explain ion drift

Answer 11

Ions emerge from electric field and drift towards detector the m/z ratio determines their velocity.

Question 12

Explain detection

Answer 12

Ions hit a negative plate and accept electrons and so cause a small current to flow. Current is determined by abundance of each ion.

Question 13

Work out the mean atomic mass

Answer 13

(Mass number x
percentage)
————-
Percentage added up

Question 14

Define 1st ionisation energy

Answer 14

Amount of energy needed to remove one mile of electrons from one mile of gaseous atoms.

Question 15

Explain the trend in successive ionisation energies.

Answer 15

General increase in amount of energy. Increase between energy levels. Because increasing effective nuclear charge.

Question 16

Show a 1st ionisation energy equation for K

Answer 16

K (g) –> K+ (g) + e-

Question 17

Show 3rd ionisation energy for K

Answer 17

K2+ (g) –> K3+ (g) + e-

Question 18

Show electron configuration

Answer 18

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6…..

Question 19

What are the two anomalies of election configuration?

Why does it make them stable ?

Answer 19

1s2 2s2 2p6 3s2 3p6 3d5 4s1

Have 2 half filled subshells

1s2 2s2 2p6 3s2 3p6 3d10 4s1

Have one half filled subshells

Question 20

Explain hunds rule

Answer 20

Go into separate parts ad then when go next to each they have mutual repulsion

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Question 21

First ionisation energies of elements

General trend across a period

Answer 21

Increases

Increasing nuclear charge
Electrons experience similar shielding
therefore increased attraction and increased 1st ionisation energy.

Question 22

First ionisation energies of elements

General trend down a group

Answer 22

Decrease

Increase nuclear charge
Electrons experience more shielding and are further away.
Therefore less attraction and decreased 1st ionisation energy.

Question 23

First ionisation energies of elements.

Group 3 less than group 2

Answer 23

Decrease

Electrons have entered a p orbital further away from nucleus.

Question 24

First ionisation energies of elements

Group 6 less than group 5

Answer 24

Decrease

Electrons start to pair in p orbital = mutual repulsion therefore less attraction and less ionisation energy